HP Deskjet 6122 Color Inkjet Printer - Manual (Page 20)

3. Set the paper width fence by carefully snapping it into the slots for the paper
size.
The slots for letter width paper are in the sides of the lower tray. Set
the width to LTR to use legal-sized paper.
1. tilt the fence forward 2. insert the fence into the appropriate slots 3. tilt
the fence back until it snaps into place